The present invention relates to underwater work-handling operations and, in particular, to portable, self-contained seawater evacuation systems adapted to be hand-carried under water to the object to be worked.
Many salvage and other under water work-handling operations are conducted by submersibles or by divers using some sort of a gripping device such as manipulator jaws to engage the work object and permit it to be moved or lifted.
Jaw-type grippers are widely used. However, situations occur in which the work objects are too large to be securely grasped so that either large, cumbersome jaws must be substituted or some other form of gripper must be provided. Also, the jaw mechanisms are rather intricate and, at times, not too reliable.
For these and other situations, the use of suction-type grippers, such as gripping pads, has been suggested. In general, the idea is for a diver to apply a pad-like suction device to the work with the pad then being pumped to evacuate seawater from its engaged surface and establish a reduced pressure area or reduced suction force. Although such suction pads clearly can be used to advantage, their implementation in an efficient, reliable seawater evacuation system has posed problems particularly because of the need to establish the suction at the working depths. Large, expensive systems, which employ special support vessels and long suction lines, of course, are possible. However, many situations better are served by simpler, inexpensive systems or units which, for example, are sufficiently small and light weight to be easily transported by the divers and manually applied to the work. Also, for reasons of simplicity and to avoid the use of the long suction lines, such portable systems preferably should be in the form of self-contained units in the sense that the motive power for establishing the suction is contained in the portable unit carried by the diver.
The present invention principally is concerned with such light-weight portable and self-contained suction systems and has, as its principal object, the provision of light-weight, simple and inexpensive systems for use underwater in the high ambient pressures.
Generally, the purposes of the invention are achieved by mounting a motor-driven pump in a thin-walled, portable casing which carries the suction-type grippers. To permit the casing to withstand ambient pressures, it is filled with a pressurized hydraulic fluid. Specifically, the motor is a hydraulic drive motor with the hydraulic fluid supplied to it from a power source. However, instead of returning the motor discharge directly to source, the motor discharges the fluid directly into the casing which itself is connected to a return line. Supply pressures then can be adjusted to achieve an interior pressure sufficient to compensate for ambient pressures.
As a further feature, the gripper members, instead of being suction or reduced-pressure devices, are differential-pressure, hold-down devices which are in the form of pads having one surface engaged with the work and the other exposed to ambient, sea-water pressure. When the engaged surface is evacuated, the pressure differential securely holds the work. The pump evacuates the seawater and, preferably, when evacuation is complete, the motor stalls. Should subsequent leakage occur, its drive is resumed to maintain the pressure differential and the holding force.